50" lear 45 twin edf 55

[Warbird]

Only a Tsunami SPT 60 ESC, Sorry !

[Babylon5]

Hi Vortices, any update on your beautiful Jet.
I am modifying one of the electra pusher jet to a twin using the 55mm Edf.
Test has indicate each fan when properly match to a good BL mtr can give very reasonable thrust and lower current.

I am planning total current of between 24 to 26 amps for the trial ..(maybe 40 amps for the hotter setup at later ..see if the current setup works) on 3 cells lipo.

Since you have experience in the twin for the Lear Jet . Any special pointer to note.

My twin setup is both fans are neck to neck mounted.

Both fans are apparently match with the ESC timing frequency reading at 540-550Hz at max power...but will check the ESC timing at other throttle settings. Using two 40 amps ESC with one ESC (call slave) +5V disable via a Y cable connectors. Only one ESC will supply the 5V to the RX via the throttle slots.

1 hz=60 rpm

Will get some picture if my experiment works.

Cheers

[Vortices]

I have set up my twin exactly the way you said it. Using Y connection and disable one of the BEC, Battery was 3s 2p parallel connection into ESCs.

I am using himax 2025-5300. Very powerful, unfortunatelt the last 20% throttle leading to max power is drwing in excess of 40 amps. Due to the weight of my lear, I need that liitle extra. If your plane is lighter, I would recommend 2025-4300 or even 2024-3700. Power thrust would be marginally lesser but amp drwn would be significantly lower.

Currently I am waiting for a new set of 60 amps esc. Will post the result once I get them. Tower pro esc was not suitable, I think tower pro esc are rated on maximum peak current not continuous current. Ordered dual sky ones now.

The other thing is to have throttle delay, even at 30% is important. this is to reduce posibility of motor shaft shearing off during throttle burst from low idle.
I set my at 70%, it also makes the fan sounds like jet engine with the characteristic slow acceleration and deceleration. Becareful though, stall recovery becomes very sluggish and landing roll becomes much longer.

cheers....any pics of your jet?

[Babylon5]

Hi Vortices, thank you. Last night tested with both motor running togather ,amps drawn was 23-24 amps looks like my Lipo hitting max discharge but the thrust feels unbelieveable strong even when I throttle to 2/3 to about 18 amps. Like the sound of the twin when it is in synch.
Will get the picture once the plane is ready.
I am fixing up the wing pieces tonight.

By the way the stock 55mm EDF will run very hot with a 4.2KV 2025 motors on 3 lipos. I am using 3.2KV 2025 motors

Cheers

[Babylon5]

twin edf 55

Hi vortices, here are some twin edf 55 pictures.
The plane maiden sucessfully last saturday. Make three flight in all.
Plane is heavy at 825 grams on a 2200maH 3 cells 12 c lipo.
Take off was straight . Both motors were running a litle bit but not noticeable to the flight.
Flight was so so...not that great .
If I go for hotter with 2 packs of 2200mAH in parallel the plane would weight
980grams. That is nearly a kilo.
It will fly like a brick.

I plan to DIY with dupron model RC plane for twin next time . With the dupron, I could built the twin EDF plane alot lighter.

Cheers

[Vortices]

Nice, what is your wing loading?

[Babylon5]

Aircraft = 29 oz
Estimated Wing area= 300sq in
Wing loading=13.92 oz per sq ft(estimate)

If I go for hotter setup with 2x1800maH, the plane will weight= 35 oz
Wing loading=16.8 oz per sq feet .
At this wing loading you need all the thrust to get it up. During landing you need a retarding parachute to slow this plane down.

Cheers

[Vortices]

ha ha ha...not a bad idea...just for the fun of it...

By the way heavier aircraft lands better in gusty conditions... more momentum.

[Babylon5]

Twin 55mm edf .One impeller came off just before taking off

Hi, try to make another flight last week. I was Taxi-ing on the runway when one of the impeller flew off...thank God it was not on the air when this happen.
I have notch the motor shaft to allow the grub screw to sit properly on the shaft but inspite of it still came off. On examinine the impeller, found the grub screw was cracked.
Looks like I have to ground the plane.

May modify my twin electra jet to 68mm edf with 6 blade impeller modified to 3 blade since it runs more efficiently , more thrust less current.
The 68mm EDF is better contructed than the current 55mmedf. Moreover, 68mm EDF comes with butterfly mounting and a very nice intake scoop.

More, when the modification is completed.

Probably have to move my electra jet to another thread since 68mm EDf will be off topic here.

Heh! heh! heh!

Cheers

[Warbird]

Hi Babylon,

Your clip rotor theory totally neglects the changes in strator requirements. It might look more efficient but at the end you loose efficiency at speed (the pressure and airflow changes with the speed of the model). Most EDF Fans (the good ones) are efficiency optimized at air speed.

The net HET-6904 Fans work amazingly well. The performance is close to the WeMoTec. I have tested it up to 800 Watt and had no exploding parts. You might want to test one for your projects.

[Vortices]

OOps, anticipating that..pls programmes throttle delay at least 10 to 20%. It is slipping not because of the axle load but more of the acceleration angular load. If you have a power analyser ofr an amp meter you will realise from zero rpm if you burst your throttle to full the amp spite is not funny, it can well be in access of 40 amps. This is due to stationary rotor has no back emf to limit amp. at 40 amp the initial torque can be very high, as a matter of fact some hotliner constantly shear motor shaft or break folding prop on start up due to same reason hence soft start or throttle delay is neccessary.

By the way, my new escs have just arrived, will be flying my lear soon...

[Warbird]

very good. Please let me know once the date and time is fixed. I bring the camera

[DT8666]

Hi Babylon,

Your clip rotor theory totally neglects the changes in strator requirements. It might look more efficient but at the end you loose efficiency at speed (the pressure and airflow changes with the speed of the model). Most EDF Fans (the good ones) are efficiency optimized at air speed.

The net HET-6904 Fans work amazingly well. The performance is close to the WeMoTec. I have tested it up to 800 Watt and had no exploding parts. You might want to test one for your projects.

Got the fan for try and the fan flow off due to my mistake of not tighten it properly the result is one blade broken

So, now follow Babylon method, cut another two blade aways and turned it to 3 blade

I really not sure what will be the airspeed result but the static test seems to have enough thrust. Will know by this weekend if Babylon's theory work well or an alternative. Else will get the another new fan blade and back to 6 blade EDF.

[Babylon5]

Guys, let me correct the fact. The twin jet is flying with the original 6 blade 55 edf. The blade comes off has got nothing to do with any modification. Moreover, I am running the fan at the lowest rpm among my brushless motor.
The fan blade comes off as Warbird pointed out is a poorly design and quality
of the materials. This is a S$10-$12 EDF. Can expect to be on par with the better Wemotec Fan...otherwise Warbird cannot sells his Wemotec Fan...sorry just joking .

If we want to discussed about the 3 blade modification it would not be done here. Lets discuss this 3 blade EDf in another thread.

cheers

[Vortices]

just to stir thing up a little more, instead of cutting of 3 out of 6 blades, I am now cutting 2mm of the entire trailling edge of every blade, essentially reducing the chord of the blades and reducing the pitch.....

will let you know the results as they come in, will fly the lear first...